As is widely known, freight car coupler assemblies and the components that make up the assemblies wear in service over time due to in service loads, natural corrosion, and natural wear and tear after thousands of miles on the rails. These worn features leave larger clearances between parts which causes more shock load on starts and stops, and increases the risk of failure. As a result, the railroad industry limits the amount of wear that can occur in a coupler assembly. These limits are typically determined through the use of gauges. Coupler assemblies that do not pass acceptable gauging criteria must be removed from the freight cars and replaced. Some parts, if heavily warn, may have to be scrapped. However, the coupler assembly, or at least some of its parts, may qualify for reconditioning by industry approved coupler reconditioners.
Theoretically, a single coupler body could be reconditioned indefinitely through a process of welding, grinding, gauging and heat treating. Reconditioning can partially restore the overall integrity of the coupler body more economically than replacing the entire coupler. However, reconditioning coupler bodies indefinitely is not currently realistic for three reasons: a) there is no established method to recondition certain coupler body features, b) certain features are very difficult to reach and restore with commonly or traditionally available shop equipment in an economically efficient manner and c) there is no way to reestablish a wearing feature's nominal position in space relative to the rest of the coupler body and its other wearing features when they were originally manufactured.
Coupler bodies are currently finished, reconditioned, or second-hand classified by referencing various features of the coupler body that may or may not be associated with one another. When service-worn castings are reconditioned, the surfaces that were previously used to gauge and then finish a new casting become unreliable for use as gauging surfaces since they are now worn. Gauging from a worn surface to finish a surface usually produces inconsistent finishing results. There is a need for a new finishing, reconditioning, or second-hand classification system that uses features that do not change over time due to natural wear or that can be used to establish a central datum feature.